Saturn has officially gained 128 new moons after an international team of astronomers used one of the most powerful telescopes on Earth to observe the planet over a period of years.
The International Astronomical Union, the authority responsible for the naming of celestial bodies, has confirmed the discovery, meaning Saturn continues to reign supreme as the 'king of the moons' in our Solar System.
Saturn now officially has 274 confirmed moons.
"Based on our projections, I don’t think Jupiter will ever catch up," says lead researcher Dr. Edward Ashton, postdoctoral fellow in the Institute for Astronomy and Astrophysics at Academia Sinica.
Discovering the new Saturn moons
Saturn's moons are interesting worlds in their own right.
Titan, for example, is Saturn's largest moon and is one of the most Earth-like bodies in the Solar System.
The Huygens spacecraft landed on Titan in 2005 and gave astronomers amazing views of its surface.
And Enceladus is an icy Saturnian moon that has a liquid ocean of water beneath its crust, making it one of the most promising places to look for signs of life beyond Earth.
The team that discovered these 128 new moons is made up of astronomers hailing from Taiwan, Canada, USA and France.
They used the Canada France Hawaii Telescope (CFHT) to observe Saturn between 2019 to 2021 and combined multiple images to achieve as strong a signal as possible.
This period of observations led to the discovery of 64 new moons around Saturn, and even more objects that, at the time, couldn't be confirmed as moons.
“With the knowledge that these were probably moons, and that there were likely even more waiting to be discovered, we revisited the same sky fields for three consecutive months in 2023,” says Ashton. "Sure enough, we found 128 new moons."
Classifying the moons
These 128 new moons at Saturn are 'irregular moons', according to the team, captured by Saturn's gravitational pull early in the history of the Solar System.
"These moons are a few kilometres in size and are likely all fragments of a smaller number of originally captured moons that were broken apart by violent collisions, either with other Saturnian moons or with passing comets," says Dr. Brett Gladman, professor in the UBC department of Physics and Astronomy (PHAS).
Solving a moon mystery
The team say that a key reason for such detailed study of Saturn's moons on this occasion was to learn more about why there is a high number of small moons compared to large moons around the planet.
They say that there was likely a moon collision around Saturn within the last 100 million years.
Otherwise, these moons would have collided with each other and been destroyed, which would reduce the ratio of small moons to large moons.
"These studies reveal that the giant planets captured some moderate-sized moons more than 4 billion years ago as the giant planets formed, and we are now seeing moons which are mostly the fragments of those originally-captured moons", says Dr. Gladman.
"Our carefully planned multi-year campaign has yielded a bonanza of new moons that tell us about the evolution of Saturn's irregular natural satellite population," says Dr. Ashton.
What next for moon-spotting in the outer Solar System? The team say they may not be able to find any more at the present time.
"With current technology I don't think we can do much better than what has already been done for moons around Saturn, Uranus and Neptune," says Dr. Ashton.
The team who discovered the 128 moons around Saturn includes Dr. Mike Alexandersen, of the Harvard Smithsonian Centre for Astrophysics and received his PhD at PHAS, as well as Dr. Jean-Marc Petit of the Observatoire de Besancon in France.
Read the paper at iopscience.iop.org/article/10.3847/2515-5172/adbf87
